Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	iShares U.S. ETF Trust
Prospectus Date	rr_ProspectusDate	Mar. 01, 2017
iShares Ultra Short-Term Bond ETF
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	iSHARES® ULTRA SHORT-TERM BOND ETF Ticker: ICSH                                 Stock Exchange: BATS
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The iShares Ultra Short-Term Bond ETF (the “Fund”) seeks to provide current income consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you will incur if you own shares of the Fund. The investment advisory agreement between iShares U.S. ETF Trust (the “Trust”) and BlackRock Fund Advisors (“BFA”) (the “Investment Advisory Agreement”) provides that BFA will pay all operating expenses of the Fund, except interest expenses, taxes, brokerage expenses, distribution fees or expenses, and extraordinary expenses. You may also incur usual and customary brokerage commissions and other charges when buying or selling shares of the Fund, which are not reflected in the Example that follows:
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund may pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 139% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	139.00%
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	You may also incur usual and customary brokerage commissions and other charges when buying or selling shares of the Fund, which are not reflected in the Example that follows:
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	The expense information in the table has been restated to reflect current management fees.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example.
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of owning shares of the Fund with the cost of investing in other funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets in a portfolio of U.S. dollar-denominated investment-grade fixed- and floating-rate debt securities that are rated BBB- or higher by S&P Global Ratings and/or Fitch Ratings, Inc. ("Fitch"), or Baa3 or higher by Moody's Investors Service, Inc. ("Moody's"), or, if unrated, determined by BFA to be of equivalent quality. Under normal circumstances, the Fund will invest primarily in fixed- and floating-rate securities maturing in three years or less. Short-term investments (generally, securities with original maturities of one year or less) held by the Fund will carry a rating in one of the highest two rating categories of at least one nationally recognized statistical ratings organization ("NRSRO") (e.g., A-2, P-2 or F2 or better by S&P Global Ratings, Moody's or Fitch, respectively), or if such investments are unrated, determined to be of comparable quality by BFA, at the time of investment. The Fund may invest in corporate and U.S. and non-U.S. government bonds, agency securities, instruments of non-U.S. issuers, privately-issued securities, asset-backed and mortgage-backed securities, structured securities, municipal bonds, repurchase agreements, money market instruments and investment companies (including investment companies advised by BFA or its affiliates). The Fund invests a significant portion of its assets in securities issued by financial institutions, such as banks, broker-dealers and insurance companies. Under normal circumstances, the dollar-weighted average life of the Fund's portfolio is expected to be one year or less, as calculated by BFA. The Fund will also seek to maintain a dollar-weighted average maturity that is less than 180 days. "Dollar-weighted average life," or "WAL," is the weighted average of the times when principal is to be repaid. "Dollar-weighted average maturity," or "WAM," is calculated by taking the average length of time to maturity (fixed-rate) or the next interest rate reset (floating-rate) for each underlying instrument held by the Fund, weighted according to the relative holdings per instrument. The Fund is an actively managed exchange-traded fund ("ETF") that does not seek to replicate the performance of a specified index. The Fund may have a higher degree of portfolio turnover than funds that seek to replicate the performance of an index. The Fund is not a money market fund and does not seek to maintain a stable net asset value of $1.00 per share. Please see the Fund's Statement of Additional Information ("SAI") for further information. The Fund may lend securities representing up to one-third of the value of the Fund's total assets (including the value of the collateral received).
Risk [Heading]	rr_RiskHeading	Summary of Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments. The Fund is subject to certain risks, including the principal risks noted below, any of which may adversely affect the Fund's net asset value per share ("NAV"), trading price, yield, total return and ability to meet its investment objective. Unlike many ETFs, the Fund is not an index-based ETF. Agency Debt Risk. The Fund invests in unsecured bonds or debentures issued by government agencies, including the Federal National Mortgage Association ("Fannie Mae") and the Federal Home Loan Mortgage Corporation ("Freddie Mac"). Bonds or debentures issued by government agencies, government-sponsored entities, or government corporations, including, among others, Fannie Mae and Freddie Mac, are generally backed only by the general creditworthiness and reputation of the government agency, government-sponsored entity, or government corporation issuing the bond or debenture and are not guaranteed by the U.S. Department of the Treasury ("U.S. Treasury") or backed by the full faith and credit of the U.S. government. As a result, there is uncertainty as to the current status of many obligations of Fannie Mae, Freddie Mac and other agencies that are placed under conservatorship of the federal government. Government National Mortgage Association ("Ginnie Mae") securities are generally backed by the full faith and credit of the U.S. government. Asset-Backed and Mortgage-Backed Securities Risk. Asset-backed securities ("ABS") and mortgage-backed securities ("MBS") or (ABS and MBS) (residential and commercial) represent interests in "pools" of mortgages or other assets, including consumer loans or receivables held in trust. ABS and MBS are subject to credit, interest rate, call, extension, valuation and liquidity risk. These securities, in most cases, are not backed by the full faith and credit of the U.S. government and are subject to the risk of default on the underlying asset or mortgage, particularly during periods of economic downturn. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain ABS and MBS. Asset Class Risk. Securities and other assets in the Fund's portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes. Assets Under Management (AUM) Risk. From time to time, an Authorized Participant (as defined in the Creations and Redemptions section of this prospectus (the "Prospectus")), a third party investor, the Fund's adviser or an affiliate of the Fund's adviser, or a fund may invest in the Fund and hold its investment for a specific period of time in order to facilitate commencement of the Fund's operations or for the Fund to achieve size or scale. There can be no assurance that any such entity would not redeem its investment or that the size of the Fund would be maintained at such levels, which could negatively impact the Fund. Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation and/or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem Creation Units (as defined in the Purchase and Sale of Fund Shares section of the Prospectus), Fund shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts and/or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in non-U.S. securities or other securities or instruments that are less widely traded. Call Risk. During periods of falling interest rates, an issuer of a callable bond held by the Fund may "call" or repay the security before its stated maturity, and the Fund may have to reinvest the proceeds in securities with lower yields, which would result in a decline in the Fund's income, or in securities with greater risks or with other less favorable features. Cash Transactions Risk. The Fund expects to effect all of its creations and redemptions for cash, rather than in-kind securities. As a result, the Fund may have to sell portfolio securities at inopportune times in order to obtain the cash needed to meet redemption orders. This may cause the Fund to sell a security and recognize a capital gain or loss that might not have been incurred if it had made a redemption in-kind. The use of cash creations and redemptions may also cause the Fund's shares to trade in the market at greater bid-ask spreads or greater premiums or discounts to the Fund's NAV. Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund's investments more than the market as a whole, to the extent that the Fund's investments are concentrated in the securities of a particular issuer or issuers, country, group of countries, region, market, industry, group of industries, sector or asset class. Credit Risk. Debt issuers and other counterparties may be unable or unwilling to make timely interest and/or principal payments when due or otherwise honor their obligations. Changes in an issuer's credit rating or the market's perception of an issuer's creditworthiness may also adversely affect the value of the Fund's investment in that issuer. The degree of credit risk depends on the issuer's financial condition and on the terms of the securities. Cyber Security Risk. Failures or breaches of the electronic systems of the Fund, the Fund's adviser, the Fund's distributor, and the Fund's other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions and negatively impact the Fund's business operations, potentially resulting in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cyber security plans and systems of the Fund's service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests. Extension Risk. During periods of rising interest rates, certain debt obligations may be paid off substantially more slowly than originally anticipated and the value of those securities may fall sharply, resulting in a decline in the Fund's income and potentially in the value of the Fund's investments. Financials Sector Risk. Performance of companies in the financials sector may be adversely impacted by many factors, including, among others, government regulations, economic conditions, credit rating downgrades, changes in interest rates, and decreased liquidity in credit markets. The impact of more stringent capital requirements, recent or future regulation of any individual financial company or of the financials sector as a whole cannot be predicted. In recent years, cyber attacks and technology malfunctions and failures have become increasingly frequent in this sector and have caused significant losses to companies in this sector, which may negatively impact the Fund. Floating Rate Notes Risk. Securities with floating or variable interest rates can be less sensitive to interest rate changes than securities with fixed interest rates, but may decline in value if their coupon rates do not reset as high, or as quickly, as comparable market interest rates, and generally carry lower yields than fixed notes of the same maturity. Although floating rate notes are less sensitive to interest rate risk than fixed-rate securities, they are subject to credit risk and default risk, which could impair their value. High Portfolio Turnover Risk. The Fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover (considered by the Fund to mean higher than 100% annually) may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities. Income Risk. The Fund's income may decline when interest rates fall because the Fund may hold a significant portion of short duration securities and/or securities that have floating or variable interest rates. The Fund's income may decline because the Fund invests in lower yielding bonds, and as the bonds in its portfolio mature, are near maturity or are called, the Fund needs to purchase additional bonds. Industrials Sector Risk. The industrials sector may be adversely affected by changes in the supply of and demand for products and services, product obsolescence, claims for environmental damage or product liability and general economic conditions, among other factors. Interest Rate Risk. An increase in interest rates may cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments. The current historically low interest rate environment increases the risks associated with rising interest rates. Issuer Risk. The performance of the Fund depends on the performance of individual securities to which the Fund has exposure. Changes in the financial condition or credit rating of an issuer of those securities may cause the value of the securities to decline. Liquidity Risk. Liquidity risk exists when particular investments are difficult to purchase or sell. This can reduce the Fund's returns because the Fund may be unable to transact at advantageous times or prices. Management Risk. The Fund is subject to management risk, which is the risk that the investment process, techniques and risk analyses applied by BFA will not produce the desired results, and that securities selected by BFA may underperform the market or any relevant benchmark. In addition, legislative, regulatory, or tax developments may affect the investment techniques available to BFA in connection with managing the Fund and may also adversely affect the ability of the Fund to achieve its investment objective. Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, periods of high volatility and disruptions in the creation/redemption process. Unlike some ETFs that track specific indexes, the Fund does not seek to replicate the performance of a specified index. Index-based ETFs have generally traded at prices that closely correspond to NAV. However, ETFs that do not seek to replicate the performance of a specified index have a limited trading history and, therefore, there can be no assurance as to whether, and/or the extent to which, the Fund's shares will trade at premiums or discounts to NAV. ANY OF THESE FACTORS, AMONG OTHERS, MAY LEAD TO THE FUND'S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. Municipal Securities Risk. Municipal securities can be significantly affected by political or economic changes as well as uncertainties in the municipal market related to taxation, legislative changes or the rights of municipal security holders, including in connection with an issuer insolvency. Municipal securities backed by current or anticipated revenues from a specific project or specific assets can be negatively affected by the inability to collect revenues for the project or from the assets. Non-U.S. Issuers Risk. Securities issued by non-U.S. issuers carry different risks from securities issued by U.S. issuers. These risks include differences in accounting, auditing and financial reporting standards, the possibility of expropriation or confiscatory taxation, adverse changes in investment or exchange control regulations, political instability, regulatory and economic differences, and potential restrictions on the flow of international capital. The Fund is specifically exposed to North American Economic Risk. Not a Money Market Fund. The Fund is not a money market fund and is not subject to the strict rules that govern the quality, maturity, liquidity and other features of securities that money market funds may purchase. Under normal circumstances, the Fund's investments may be more susceptible than a money market fund is to credit risk, interest rate risk, valuation risk and other risks relevant to the Fund's investments. The Fund does not seek to maintain a stable net asset value of $1.00 per share. Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund and BFA seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address these risks. Privately-Issued Securities Risk. The Fund will invest in privately-issued securities, including those that are normally purchased pursuant to Rule 144A or Regulation S promulgated under the Securities Act of 1933, as amended (the "1933 Act"). Privately-issued securities are securities that have not been registered under the 1933 Act and as a result are subject to legal restrictions on resale. Privately-issued securities are not traded on established markets and may be illiquid, difficult to value and subject to wide fluctuations in value. Delay or difficulty in selling such securities may result in a loss to the Fund. Repurchase Agreement Risk. A repurchase agreement is an instrument under which the purchaser (i.e., the Fund) acquires a security and the seller agrees, at the time of the sale, to repurchase the security at a mutually agreed upon time and price. Repurchase agreements may be construed to be collateralized loans by the purchaser to the seller secured by the securities transferred to the purchaser. If a repurchase agreement is construed to be a collateralized loan, the underlying securities will not be considered to be owned by the Fund but only to constitute collateral for the seller's obligation to pay the repurchase price. If the seller defaults on its obligation under the agreement, the Fund may suffer delays and incur costs or lose money in exercising its rights under the agreement. If the seller fails to repurchase the security and the market value of the security declines, the Fund may lose money. Risk of Investing in Developed Countries. The Fund's investment in developed country issuers may subject the Fund to regulatory, political, currency, security, economic and other risks associated with developed countries. Developed countries tend to represent a significant portion of the global economy and have generally experienced slower economic growth than some less developed countries. In addition, developed countries may be adversely impacted by changes to the economic conditions of certain key trading partners, regulatory burdens, debt burdens and the price or availability of certain commodities. Risk of Investing in the United States. The Fund has significant exposure to U.S. issuers. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure. Securities Lending Risk. The Fund may engage in securities lending. Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investments made with cash collateral. These events could also trigger adverse tax consequences for the Fund. Sovereign and Quasi-Sovereign Obligations Risk. The Fund may invest in securities issued by or guaranteed by sovereign governments, which may be unable or unwilling to repay principal or interest when due. In times of economic uncertainty, the prices of these securities may be more volatile than those of corporate debt obligations or of other government debt obligations. U.S. Treasury Obligations Risk. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund's U.S. Treasury obligations to decline. Valuation Risk. The sale price the Fund could receive for a security or other asset may differ from the Fund's valuation of the security or other asset, particularly for securities or other assets that trade in low volume or volatile markets or that are valued using a fair value methodology. In addition, the value of the securities or other assets in the Fund's portfolio may change on days or during time periods when shareholders will not be able to purchase or sell the Fund's shares.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table that follow show how the Fund has performed on a calendar year basis and provide an indication of the risks of investing in the Fund. Both assume that all dividends and distributions have been reinvested in the Fund. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Supplemental information about the Fund’s performance is shown under the heading Total Return Information in the Supplemental Information section of the Prospectus.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table that follow show how the Fund has performed on a calendar year basis and provide an indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-iShares (1-800-474-2737) (toll free)
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.iShares.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Year by Year Returns (Years Ended December 31)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	The best calendar quarter return during the periods shown above was 0.32% in the 3rd quarter of 2016; the worst was -0.06% in the 3rd quarter of 2015. Updated performance information is available at www.iShares.com or by calling 1-800-iShares (1-800-474-2737) (toll free).
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2016)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns in the table above are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state or local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on an investor's tax situation and may differ from those shown, and after-tax returns shown are not relevant to tax-exempt investors or investors who hold shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	Fund returns after taxes on distributions and sales of Fund shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sale of Fund shares. As a result, Fund returns after taxes on distributions and sales of Fund shares may exceed Fund returns before taxes and/or returns after taxes on distributions.
iShares Ultra Short-Term Bond ETF | iShares Ultra Short-Term Bond ETF
Risk/Return:	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.08%	[1]
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none	[1]
Other Expenses	rr_OtherExpensesOverAssets	none	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.08%	[1]
1 Year	rr_ExpenseExampleYear01	$ 8
3 Years	rr_ExpenseExampleYear03	26
5 Years	rr_ExpenseExampleYear05	45
10 Years	rr_ExpenseExampleYear10	$ 103
2014	rr_AnnualReturn2014	0.44%
2015	rr_AnnualReturn2015	0.17%
2016	rr_AnnualReturn2016	1.19%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	best
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2016
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	0.32%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	worst
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.06%)
One Year	rr_AverageAnnualReturnYear01	1.19%
Since Fund Inception	rr_AverageAnnualReturnSinceInception	0.59%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 11, 2013
iShares Ultra Short-Term Bond ETF | Return After Taxes on Distributions | iShares Ultra Short-Term Bond ETF
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	0.80%	[2]
Since Fund Inception	rr_AverageAnnualReturnSinceInception	0.32%	[2]
iShares Ultra Short-Term Bond ETF | Return After Taxes on Distributions and Sale of Fund Shares | iShares Ultra Short-Term Bond ETF
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	0.67%	[2]
Since Fund Inception	rr_AverageAnnualReturnSinceInception	0.33%	[2]
iShares Ultra Short-Term Bond ETF | Bank of America Merrill Lynch 6-month US Treasury Bill Index (Index returns do not reflect deductions for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	0.67%	[3]
Since Fund Inception	rr_AverageAnnualReturnSinceInception	0.34%	[3]

[1] The expense information in the table has been restated to reflect current management fees.

[2] After-tax returns in the table above are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown, and after-tax returns shown are not relevant to tax-exempt investors or investors who hold shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs"). Fund returns after taxes on distributions and sales of Fund shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sale of Fund shares. As a result, Fund returns after taxes on distributions and sales of Fund shares may exceed Fund returns before taxes and/or returns after taxes on distributions.

[3] The Bank of America Merrill Lynch 6-month US Treasury Bill Index is an unmanaged index that measures the performance of government securities with less than 6 months remaining to maturity.